If you use filo dough take two layers for each long roll and add the filling according to directions below and proceed.

Directions for filling:
Wash and squeeze water out of chopped spinach (if using frozen leaf spinach, squeeze water out completely). Put oil in pan and add finely chopped onions and cook stirring until transparent but not brown. Add spinach and stir well until spinach is wilted. Add salt and pepper and set aside to cool.
Directions for preparing dough:
Put 4 cups of flour in a large bowl. Make a well in flour, break in eggs, add salt, oil, vinegar and water (the latter gradually) as you mix all with a wooden spoon. When all the water is added, use hands to make dough consistent, kneading gently. Let stand for 10 minutes (you can make the filling while dough rests). Divide dough into four or five pieces making them into balls. Set aside and cover with dish towel. Start with one ball on a floured board, roll out using enough flour over it so it will not stick on the board or on the rolling pin. Roll until it's 20 inches in diameter. Cut into two half circles. Pulling the long end before you put two tablespoons filling along the edge and brush the rest of the sheet dough with melted butter them roll it into long 1 1/2 inch wide cylinder. Curl this and place it in the middle of an oiled, large Teflon pan. Continue with the other half in the same way and with the remaining three balls adding each cylinder enlarging it toward the sides of the pan. Brush top with butter and cook on top of moderate burner. When bottom is golden, place the back of a tray on top of pan and turn it upside down and slide the uncooked top on bottom of pan and continue cooking this side until it's golden and cooked. Serve hot, cutting it like a pie.